1. Field of the Invention
The present invention relates to devices useful for lifting and removing objects from spaces where access is restricted. More particularly, the present invention relates to detachable wafer carrier handle assemblies and combinations thereof for use in loading and unloading vertical wafer carriers into and out of equipment and transporting the wafer carriers between equipment.
2. Description of the Invention Background
Semiconductor devices such as transistors, are commonly mass produced by simultaneously forming a plurality of semiconductor devices on a wafer shaped substrate, or wafer, composed of a semiconductor material, such as monocrystalline silicon. The processed wafers are then cut up to separate the individual devices for use in a variety of applications. Many of the processing steps in the formation of semiconductor devices are not amenable to continuous processing and, therefore, must be processed in batch type processing stages, which tend to lower production capacity due to process downtime involved with loading, unloading and transporting the batches. Processing equipment has been designed to increase production capacity by simultaneously or continuously treating a number of wafers in a semi-batch processing mode. The wafers are processed in bulk through the use of wafer carriers that have been designed to hold and separate a plurality of wafers allowing for the simultaneous or continuous processing of the batch. The wafer carriers also serve to minimize the need for human contact with the wafers during processing which could result in contamination of the wafers. Various designs and material of construction are used in the wafer carriers depending upon the processing stages in which the wafer carrier is to be used, but in most carriers generally consist of a base containing a plurality of slots or grooves that serves to separate the wafers in a cassette-type arrangement.
Two different types of materials are commonly used for wafer carriers in the industry. In high temperature processing steps, greater than about 200.degree. C., wafer carriers are often made from a plurality of quartz or other temperature resistant rods that form a "basket" or "rack" for supporting the wafers. In low temperature processing steps, wafer carriers are typically made of molded plastics, such as polytetrafluoroethylene (Teflon.RTM.) or polypropylene. In addition to temperature considerations, the carrier design is dependent upon the processing step in which the carrier is used. Some carriers, known as low profile carriers, are designed to provide relatively unrestricted access to the wafers within the carrier. Other carriers, known as high profile carriers, are designed to more fully enclose and protect the wafers.
One limiting aspect of the overall production capacity of the semiconductor devices is the time involved in loading and unloading the wafer carriers in the equipment for each batch type processing stage and transferring the wafer between stages. In addition, these handling operations also greatly increase the potential for physical damage to and contamination of the wafers. In most instances, the wafers are generally stored and transported in the carriers in which the wafers are in a vertically upright, horizontally spaced array. However, in a number of processes the faces of the wafers must be horizontally oriented and the wafers must be loaded into the equipment using a vertical wafer carrier in which the faces of the wafers are oriented horizontally, in a vertically spaced array.
Vertical wafer carriers typically have one end that contains a handle to enable the carrier to be lifted in a stable manner. The opposite end of the carrier is designed so that the carrier can stand on end. The wafer processing equipment typically must be loaded from either the top or the side of the equipment. In top loading equipment, the vertically oriented carrier can be lowered into the processing equipment by the handle of the carrier in a stable, controlled manner. However, when loading a vertical carrier horizontally into side loading equipment, the vertical carrier generally can not be held by the handle from above the carrier within the confines of the processing equipment and the carrier must be supported in a different manner. Supporting the carriers from below the opposite end of the carrier or the handle, or by the sides imparts instability to the carrier and requires precise control of the carrier to avoid tilting the carrier during the loading and unloading operation that could result in dumping the wafers out of the carrier or wedging the carrier in the equipment.
One prior method of manipulating carriers having an open handle extending from their upper surface included the use of a removable handle. Such handle included a T-shaped frame having a single handle extending from one side of the vertical member of the T. Two spaced elongated wedge members extend from the other side of the horizontal member of the T. The wedge members serve to engage the handle on the carrier. This method, however, was flawed in that it required a user to manipulate a rather heavy carrier filled with wafers with only one hand. This proved to be strenuous and has led to dropping of carriers and wafers.
The present invention is directed to providing an apparatus to efficiently and safely load and unload a vertically oriented wafer carrier in a substantially horizontal direction which overcomes, among others, the above-discussed problems so as to increase the stability, efficiency and safety of the loading and unloading of vertically oriented wafer carriers.